Ferrocene polythia coronands

Sulfur-containing ferrocene macrocyclic receptors are known containing from three to six sulfur atoms and one or two ferrocene moieties [109-112], Examples include 57-59. 

The sulfur-containing receptors form host-guest complexes with soft metal cations such as Cu+, Ag+, Hg , and Pd their stability depends on the size of macrocycle and in some cases spectral data suggest an interaction between the iron atom and the metal coordinated by the macrocycle, as shown in 60. 

Nitrogen can be incorporated in the macrocycle to give aza-thia hosts, 61 and 62 [113, 114], 

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